1) Field of the Invention
The invention herein relates to a permanent magnet brake mechanism for general applications such as a brake mechanism on health and therapeutic exercise machines that provides for simplified structural assembly and installation, stable performance and, furthermore, an complete structure in which the brake torque adjustment is continuous and stepless.
2) Description of the Prior Art
The brake mechanisms on current exercise machines or therapeutic machines are typically friction- and hydraulic-type or electric fan- or generator-based units; of these, the shortcomings of friction-type brake devices include wear and unstable braking (loading), the drawbacks of hydraulic-type brake devices include oil leakage, noise, and reduced braking at high temperatures; the defects of electric fan-based devices include overly large dimensions, unattractive appearance, a narrow load range, and difficult adjustment; and the negative aspects of the generator-based devices are structural complexity and high purchase prices.
Referring to FIG. 1 and FIG. 2, since the product structure of the currently marketed, manufacturer researched and developed "Permanent Magnet-type Adjustable Brake Device" utilizes an electrical conductor to vary the magnetic flux, back electromagnetic force (EMF) is generated in the circuit of the electrical conductor, producing local current or so-called eddy currents; according to Lenz's Law, the direction of the eddy currents sets up a reverse current flow that varies the original magnetic flux, with the square ratio of the directional torque and flux density permeating the air calculated using Maxwell's equation.
Based on the foregoing fundamental principle, the permanent magnet-type adjustable brake device of the said disclosure is comprised of bearings 11 inside a neck 10, a single-direction flywheel assembly 12 of a rotatable outer hub 1 disposed adjacent to the neck 10, a main shaft 3 inserted through the bearings 11 mounted in the rotatable outer hub 1, a sliding seat 4 sleeved on the main shaft 3 and situated within the interior spatial confines of the rotatable outer hub 1 and, furthermore, has a permanent magnet 41 along its outer circumference, with the sliding seat 4 also positioned on the outer side of the main shaft 3 and, furthermore, a return spring 51 installed between the main shaft 3 and the sliding seat 4, a brake line 52 that is connected to the sliding seat 4 and, furthermore, controls the movement of the sliding seat 4, and a minimum of one guide key 53 at the interior side of the brake line 52 that provides for the positioning of a mounting frame 5 when the sliding seat 4 slides along the main shaft 3; an annular groove 13 of an indented profile is formed along the circumferential edge of the said rotatable outer hub 1 that accommodates the entry of the permanent magnet 41 of the sliding seat 4 and, furthermore, a guide ring 2 is situated along both the upper and lower interior surfaces of the said annular groove 13 such that when the said structural components are assembled, the upper and lower surfaces of the permanent magnet 41 become physically coupled which increases the unit loading capacity and enables a reduction of structural dimensions.
In the said structural assembly, although the upper and lower surfaces of the permanent magnet 41 are physically coupled to thereby increase the unit loading capacity and reduce the structural dimensions, since an annular groove 13 of an indented profile must be formed along the circumferential edge of the said rotatable outer hub 1, the initial fabrication of the rotatable outer hub 1 involves an inexpedient finishing procedure and after the annular indentation is formed in the surface, the guide ring 2 must be inserted inside which similarly results in assembly inconveniences; notably, when the brake line 52 is pulled to control the movement of the sliding seat 4, this causes the permanent magnet 41 along its circumferential edge to be extended in or out of the indented profile of the annular groove 13 in a reciprocal path of operational movement, thereby enabling the variation of the coupling surface area size between the permanent magnet 41 and the guide ring 2 and proportionately varying the magnetic flux density, with the process producing an increase in temperature that cannot be effectively diverted or dissipated that seriously decreases the quality of powderized metal permanent magnets and thus adversely affects the objectives and performance of the entire structure.
Therefore, to remedy the said shortcomings of the conventional structure, the inventor of the invention herein, based on many years of experience gained while engaged in the marketing and production of various types of health and therapeutic exercise machines as well as after-sales consumer feedback, conducted extensive research that was additionally supported by research results accumulated from manufacturing experience which culminated in the successful completion of the invention herein and its submittal for purposes of patent application.